Adjustable-volume volumetric injection pump



Aug. 12, 1958 l.. PERAs 2,846,991

ADJUSTABLE-VOLUME VOLUMETRIC INJECTIQN PUMP Filed oct. 11. 195s 2 sheets-sheet 1 FIG. 1.

9 INVENTOR zzcz'en/ Ferns ATTORNEY ADJUSTABLE-VOLUME VOLUMETRIC INJECTION PUMP 2 Sheets-Sheet 2 L. PRAS Aug. 12, 1958 Filed oci. 11, 1955 FIG. 5-

ii l

INVENTOR lucien .perds BY f ATTORNEY United States Patent ADJUSTABLE-VOLUME VOLUMETRTC INJECTIG'N PUMP Lucien Peras, Billancourt, France, assigner to Regie Nationale des Usines Renault, Billancourt, France Application October 11, 1955, Serial No. 539,898 `Claims priority, application France October 15, 1954 8 Claims. (Cl. 1'23-140) This invention relates to volumetric pumps and more particularly to an improved device for modifying the volume of the pump in accordance with the intake manifold pressure.

For controlling the quantity of fuel injected in fuelinjection pumps for an internal combustion engine, the U. S. Patent 2,727,504 of December 20, 1955, in the applicants name, provides chiey for the application of engine manifold pressure to a combination of two diaphragms of different diameters instead of a single diaphragm. The action on the second diaphragm taking place only when the air inlet or manifold intake pressure is above a certain value. This no longer gives the pump a single delivery line such as OF (Fig. l), but a combination of two straight lines OE and EG intersecting at a point E, the delivery characteristic from the point O to the point E then being given solely by the first diaphragm, and from the point E to the point G by the combination of the two diaphragms acting in parallel.

The present invention has the object of providing a more compact device, of simpler construction and simpler in operation.

To this end, a single diaphragm is used instead of two. The diaphragm is divided into two active surfaces, each corresponding to the two surfaces provided in the foregoing application. The first active surface being formed by gripping the center of 'the diaphragm between two circular plates, and the second active surface by gripping the diaphragm between two annular plates whereby the displacement of this surface is independent of Ithe displacement of the central circular surface because of the flexibility of the diaphragm.

Fig. l is a diagram of air and fuel deliveries as a function of inlet pressure in an ordinary pump and in a pump of the type in question;

Fig. 2 is a transverse section of the device according to the present invention;

Fig. 3 is a cross-section showing a particular application of the invention to an injection pump.

With reference to Fig. 2, it will be noted that the diaphragm 1 is held between a case 2 and a case 3. The space 3a between the diaphragm and the case 3 is in communication with the atmosphere. The space 2a at the side of the case 2 is in communication with the inlet pipe or intake manifold of the engine via the conduit 11. The diaphragm 1 is gripped at the center between the plate 4 and the vplate S of the same diameter, the plate 5 having three ears 6 equally distributed about its periphery, and slightly displaced from the plane of the plate.

These two plates are engaged by the two nuts 7 screwed on to the rod 9 in such a way that movement of the central surface of the diaphragm is directly transmitted to this rod 9, which controls the variation in delivery of the pump (not shown). The compartment 2a contains a very stiff spring 8, which acts against the depression prevailing in this compartment 2a, and determines the position of the plate 5, and thus of the axis 9. A very exible ICC compensating spring 13 is fitted in opposition in the compartment 3a, and bears against the-plate 5.

Two rims 10 and 14, held together with the'diaphragms between them, by small bolts not shown, are disposed about the plates 4 and 5. The plate 14 situated in the compartment 2-has an annular edge 16 which can abut against the internal surface of the case 2. Three springs disposed at such as 12, likewise bear against the rim 14. These three springs are very exible. The manifold pressure in the compartment 2a is conveyed by the pipe 11 via a three-way cock 15. The surface of these rims 10 and 14 is greater than that of the central plates.

The device operates as follows:

When the engine is running normally, the three way cock is disposed as indicated in the figure so that the pressure prevailing in the air inlet pipe is set up in the chamber 2a. If the absolute pressure prevailing in the compartment 2a is below the value C (Fig. l), the combination of the three springs 12 is insufficient to oppose atmospheric pressure, andthe combination of the rims 10 and 14 abuts via the edge 16 against the plane wall of the compartment 2. The action of atmospheric pressure is consequently being exerted at this moment on the central plates 4 and 5 as if the rims 10 and 14 were a fixed support. The position of the rod 9 consequently depends only on the position of the plates 4 and 5, thisV being determined by the characteristic of the spring 8, and the action of depression on the corresponding surface on the plate 4. Fuel delivery of the pump consequently follows the characteristic ME in Fig. l.

When the load on the engine increases, and the absolute pressure becomes greater than C, while remaining lower than atmospheric pressure, the action of the forces acting on the rims 10 and 14 is modified; the action of the springs 12 bringing it to the low value of the force due to the pressure. The combination of these rims 10 and 14 is then spaced away from the case 2, and bears against the ears 6 of the plate 5, in such a way that they transmit to this plate the differential force between the springs 12 vand the difference between the pressures acting on the surfaces of the rims 10, 14, this force having become positive.- The surface of these rims is greater than the surface of the central plates, and a fairly small Variation in inlet pressure produces a fairly large variation in pressure on the diaphragm, and the differential force thus applied to the plate 5 adds to the force of the spring 8, and changes the position of the rod 9 in such a way that the new delivery law of the pump corresponds to the line EG in Fig. 1.

If the rotary member of the cock 15 is turned in such a way as to put the compartment l2a in communication with the atmosphere, a choke is produced, as in the foregoing application, the diaphragm then being unbalanced, and subjected to the unilateral action of the resultant of the forces of the springs 8, 12 and 13.

In the particular form of embodiment illustrated in Fig. 3, the same elements as in Fig. 2 are shown with the same reference numbers, with this difference, however, that the control rod 9 is s-ituated on the side of the case 2, and no longer on the side of the case 3, which makes it necessary to seal the passage of the rod 9 by means of the diaphragm 36. In addition, the spring 8 is a leaf spring bearing against the rod 9, but fitted on the other side of the pump, which is entirely traversed by the rod 9.

It will be noted that the action of this spring 8 is exactly the .same as the action of the spring with the same reference in Fig. 2.

The rod 9 acts on an abutment 37 regulating the lift of the circularly distributed contacts 38 serving to pro- 3. vide pulsations for the injection of fuel under pressure.

I claim: 1. In an improved adjustable-volumevolumetric injec- `tion pump particularly intended for injecting fuel into engines having an intake manifold, means for varying the volumetric output of the pump, a single pressure-responsive member connected to said output varying means and having two sides, communication means between one side of said pressure-responsive means and the intake manifold so as to be responsive to the pressure therein,

means defining a first control portion and a second control portion in said pressure-responsive member so that the kportions are independently and cooperatively responsive to said intake manifold pressures, means permitting a Ypredetermined movement of said rst portion whena predetermined manifold pressure `range less than atmospheric pressure exists and 'a predetermined cooperative movement of both portions when a manifold pressure range higher than said predetermined manifold pressure range exists, whereby the means for varying the volumetric output of the pump Varies the output as a function of the load on the engine and in one range of intake manifold pressures said output varying means is subject only to the first of said control portions and in another range of intake manifold pressures, said output varying means is subject to both of said control portions.

2. In an improved adjustable-volume-volumetric injection pump particularly intended for injecting fuel into engines having an intake manifold, means for Varying the volumetric output of the pump, a single pressureresponsive member connected to said output varying means and having two sides, communication means for having one side of said pressure-responsive means communicate with the pressure in the intake manifold so as to be responsive thereto and for the other side to communicate with the atmosphere so as to be responsive to atmospheric pressure, means defining a rst control portion and a second control portion in said pressure-responsive member so that the portions are independently and cooperatively responsive to said intake'manifold pressures, means permitting a predetermined movement of said rst portion when a predetermined manifold pressure range less than atmospheric pressure exists and a predetermined cooperative movement of both portions when a manifold pressure range higher than said predetermined manifold pressure range exists, whereby the means for varying the volumetric output of the pump varies the output as a function of the load on the engine and in one range of intake manifold pressures said output varying means is subject only to the rst of said control portions in another range of intake manifold pressures said output varying means is subject to both of said control portions.

3. In a pump according to claim 2, in which said means for varying the volumetric output of the pump is connected to said first portion.

4. In a pump according to claim 2, in which said second portion has a greater pressure-responsive area than said first portion whereby when said output varying means is subject to both of said control portions the effective control area is the total of the areas of both portions, thereby a small variation in manifold pressure produces a large variation in the pressure acting on said pressureresponsive member.

5. In a pump according to claim 2, in which said pressure-responsive member comprises a single diaphragm.

6. In a pump according to claim 2, in which said pressure-responsive member comprises a singlediaphragm, and in which said means defining a iirst control portion and a second control portion on said pressure-responsive means comprises a pair of substantially circular discs disposed'on said diaphragm one on either side of the diaphragm and a pair of annular members one on either side of said discs, said discs having means for engaging the annular members for making said portions cooperatively responsive to said intake manifold pressures.

7. In a pump according t0 claim 6, in which said discs and said annular members are spring biased.

8. In a pump according to claim 2, in which means is provided to cut olf said intake pressure acting on the pressure-responsive means and lto cut-in atmospheric pressure on the side in communication with said manifold pressure.

References Cited in the tile of this patent UNITED STATES PATENTS 2,673,556 Reggio Mar. 30, 1954 2,727,504 Peras Dec. 20, 1955 FOREIGN PATENTS 642,214 Germany Feb. 25, 1937 

